<?php
  /**
   * @package dompdf
   * @link    http://dompdf.github.com/
   * @author  Benj Carson <benjcarson@digitaljunkies.ca>
   * @author  Fabien Ménager <fabien.menager@gmail.com>
   * @license http://www.gnu.org/copyleft/lesser.html GNU Lesser General Public License
   */
  namespace Dompdf\FrameReflower;
  
  use Dompdf\Frame;
  use Dompdf\FrameDecorator\Block as BlockFrameDecorator;
  use Dompdf\FrameDecorator\Page as PageFrameDecorator;
  
  /**
   * Reflows pages
   *
   * @package dompdf
   */
  class Page extends AbstractFrameReflower
  {
  
      /**
       * Cache of the callbacks array
       *
       * @var array
       */
      private $_callbacks;
  
      /**
       * Cache of the canvas
       *
       * @var \Dompdf\Canvas
       */
      private $_canvas;
  
      function __construct(PageFrameDecorator $frame)
      {
          parent::__construct($frame);
      }
  
      function apply_page_style(Frame $frame, $page_number)
      {
          $style = $frame->get_style();
          $page_styles = $style->get_stylesheet()->get_page_styles();
  
          // http://www.w3.org/TR/CSS21/page.html#page-selectors
          if (count($page_styles) > 1) {
              $odd = $page_number % 2 == 1;
              $first = $page_number == 1;
  
              $style = clone $page_styles["base"];
  
              // FIXME RTL
              if ($odd && isset($page_styles[":right"])) {
                  $style->merge($page_styles[":right"]);
              }
  
              if ($odd && isset($page_styles[":odd"])) {
                  $style->merge($page_styles[":odd"]);
              }
  
              // FIXME RTL
              if (!$odd && isset($page_styles[":left"])) {
                  $style->merge($page_styles[":left"]);
              }
  
              if (!$odd && isset($page_styles[":even"])) {
                  $style->merge($page_styles[":even"]);
              }
  
              if ($first && isset($page_styles[":first"])) {
                  $style->merge($page_styles[":first"]);
              }
  
              $frame->set_style($style);
          }
      }
  
      //........................................................................
  
      /**
       * Paged layout:
       * http://www.w3.org/TR/CSS21/page.html
       */
      function reflow(BlockFrameDecorator $block = null)
      {
          $fixed_children = array();
          $prev_child = null;
          $child = $this->_frame->get_first_child();
          $current_page = 0;
  
          while ($child) {
              $this->apply_page_style($this->_frame, $current_page + 1);
  
              $style = $this->_frame->get_style();
  
              // Pages are only concerned with margins
              $cb = $this->_frame->get_containing_block();
              $left = $style->length_in_pt($style->margin_left, $cb["w"]);
              $right = $style->length_in_pt($style->margin_right, $cb["w"]);
              $top = $style->length_in_pt($style->margin_top, $cb["h"]);
              $bottom = $style->length_in_pt($style->margin_bottom, $cb["h"]);
  
              $content_x = $cb["x"] + $left;
              $content_y = $cb["y"] + $top;
              $content_width = $cb["w"] - $left - $right;
              $content_height = $cb["h"] - $top - $bottom;
  
              // Only if it's the first page, we save the nodes with a fixed position
              if ($current_page == 0) {
                  $children = $child->get_children();
                  foreach ($children as $onechild) {
                      if ($onechild->get_style()->position === "fixed") {
                          $fixed_children[] = $onechild->deep_copy();
                      }
                  }
                  $fixed_children = array_reverse($fixed_children);
              }
  
              $child->set_containing_block($content_x, $content_y, $content_width, $content_height);
  
              // Check for begin reflow callback
              $this->_check_callbacks("begin_page_reflow", $child);
  
              //Insert a copy of each node which have a fixed position
              if ($current_page >= 1) {
                  foreach ($fixed_children as $fixed_child) {
                      $child->insert_child_before($fixed_child->deep_copy(), $child->get_first_child());
                  }
              }
  
              $child->reflow();
              $next_child = $child->get_next_sibling();
  
              // Check for begin render callback
              $this->_check_callbacks("begin_page_render", $child);
  
              // Render the page
              $this->_frame->get_renderer()->render($child);
  
              // Check for end render callback
              $this->_check_callbacks("end_page_render", $child);
  
              if ($next_child) {
                  $this->_frame->next_page();
              }
  
              // Wait to dispose of all frames on the previous page
              // so callback will have access to them
              if ($prev_child) {
                  $prev_child->dispose(true);
              }
              $prev_child = $child;
              $child = $next_child;
              $current_page++;
          }
  
          // Dispose of previous page if it still exists
          if ($prev_child) {
              $prev_child->dispose(true);
          }
      }
  
      //........................................................................
  
      /**
       * Check for callbacks that need to be performed when a given event
       * gets triggered on a page
       *
       * @param string $event the type of event
       * @param Frame $frame the frame that event is triggered on
       */
      protected function _check_callbacks($event, $frame)
      {
          if (!isset($this->_callbacks)) {
              $dompdf = $this->_frame->get_dompdf();
              $this->_callbacks = $dompdf->get_callbacks();
              $this->_canvas = $dompdf->get_canvas();
          }
  
          if (is_array($this->_callbacks) && isset($this->_callbacks[$event])) {
              $info = array(
                  0 => $this->_canvas, "canvas" => $this->_canvas,
                  1 => $frame, "frame" => $frame,
              );
              $fs = $this->_callbacks[$event];
              foreach ($fs as $f) {
                  if (is_callable($f)) {
                      if (is_array($f)) {
                          $f[0]->{$f[1]}($info);
                      } else {
                          $f($info);
                      }
                  }
              }
          }
      }
  }